technology shouldn't be the problem. WhatsApp managed to support old phones as well.
A technological solution would be : sending an sms to a specific government number.( free of course )
Again : technology shouldn't create problems. Phones should just be an easy alternative to paperwork. If "you" don't have a phone, you should still be able to vote with paper.
Problem solved.
Not at all. The problem is now two problems, each with associated risks and caveats. Now we've got hanging chads AND repudiation of several sorts.